A recurring problem with man-machine interfaces is information overload. Even a well-designed graphical interface may deliver more information than a viewer is able to absorb. As the amount of displayed information increases, the ability of a viewer to identify what information is relevant to a decision decreases. This problem is especially acute when displayed data frequently changes and the changes are visually subtle.
An example of an interface in which the relevance of data is easily lost to the viewer is an administration tool for configuring and monitoring a search engine running in a distributed hardware landscape. The user interface of such an administration tool may offer different views that display data related to specific aspects of the search engine, such as load balancing, fail over, resource consumption of the different search engine services, etc.
FIG. 1 shows a view of an administration tool that lists all currently existing trace files. Each record of a trace file may indicate a program action at a particular time. The user may select one or more trace files (e.g., selected items 101-105) to be displayed in a separate window.
FIG. 2 shows how the five trace files selected in FIG. 1 may be displayed in one common window. The clocks on the hosts on which the search engine is running are typically all synchronized so that the trace files from different hosts may be compared. When investigating several trace files at one time, it is important to find identical or at least similar time stamps in different trace files in order to compare events. If an error is detected in one trace file, a system administrator will want to know what happened on the other services of the search engine at the same time.
The window in FIG. 2 has only one vertical scroll bar. Movement of the slider 210 of the scroll bar is translated into individual scrolling movements in each of the panes 201-205 so that similar or identical time stamps are displayed to the user. Each pane may be resized by moving a splitter bar 215; the size of the panes may be equalized by selection of an “equalize” button 232; the trace file data may be refreshed by selection of a “refresh” button 234; and the multiple pane view may be closed by selection of a “close” button 230. This interface and an architecture implementing this interface have been described in co-pending U.S. patent application Ser. No. 11/098,958 filed 4 Apr. 2005, entitled “System And Method For Scrolling Data”, which is incorporated herein by reference for its explanation of how to implement the interface and architecture on a computer system.
While the interface illustrated in FIG. 2 simplifies viewer identification of time-related events by allowing trace files to be compared side-by-side, information overload increases as more trace files and panes are added, or more items are displayed in individual panes. However, selecting fewer files or displaying fewer events makes it less likely that the critical information needed to understand what happened will be displayed.
Thus, when simultaneously displaying multiple series of items side-by-side, there is a need to distinguish displayed information in a way that assists a viewer in discerning relevance.